You signed a contract? This falls under my ISP's TOS. Anyway, what I would do if I were you is run your Debian server at home, but get a tiny Linode through wh

You signed a contract? This falls under my ISP's TOS. Anyway, what I would do if I were you is run your Debian server at home, but get a tiny Linode through which your server VPNs, not just so your ISP can't parse the traffic (they're probably considerably more snoopy than Linode and their upstream, leaving the NSA aside for the moment), but also so you don't run into problems common to running an email server at home, e.g. having your outgoing emails bounced because they come from a residential IP block. As far the constrictive upstream with big files? I'd rely on Dropbox or Spideroak, depending on how much I valued convenience (Dropbox) over security (Spideroak).